Feeding mechanism for printing press



Feb. 9, 1965 L. E. LOPER WW FEEDING MECHANISM FOR PRINTING PRESS Filed May 10, 1962 2 Sheets-Sheet 1 Feb. 9, 1 L. E. LOPER FEEDING MECHANISM FOR PRINTING PRESS Filed May 10, 196? 2 Sheets-Sheet 2 wwwmz: 50

A'ffarruyr t States Pate This invention relates to an improved feed mechanism for an offset printing press of the duplicator type commonly known as a multilith. The feed mechanism that has been characteristic of such presses for many years comprises a pair of relatively long unyielding all metal vacuum shoes mounted on a horizontally extending motion bar. The horizontal motion bar is actuated by a system of rocker arms driven by cam means in opposition to cooperating spring means, the motion bar being reciprocally translated laterally of its axis along a generally upright arc and being simultaneously rotated about its longitudinal axis. As a result the lower ends of the two vacuum shoes reciprocate between relatively low rearward positions to pick up printing stock and higher forward positions to release the stock to the printing press. The vacuum action of the shoes is synchronized with the reciprocative movement of the shoes and air jets on the two opposite sides of the supply stack are also synchronized with the reciprocative movement to facilitate the pick-up action.

The described feed mechanism is effective for its purpose if used to handle relatively light paper that lies flat on the supply stack and separates easily from the supply stack. Unfortunately, however, the feed mechanism functions in a faulty manner and may even fail to function at all for feeding other kinds of stock, notably relatively heavy and stiff stock. Any stock that is slightly curved or curled longitudinally or laterally causes trouble and especially so if the paper is relatively stiff.

The present invention is based on a number of interrelated concepts. One concept is that the path of movement of the vacuum shoes may be changed for increased efiiciency and that such an improvement may be accomplished by mounting suitable arm means on the conventional motion bar for swinging movement in response to rotation of the motion bar. A second concept is that such an arm means may extend downward to locate the vacuum shoes at a relatively low level. Another concept is that with the low level location of the vacuum shoes, the vacuum shoes may be relatively short in vertical dimension. In contrast to a long vacuum shoe, a short vacuum shoe may be tilted to conform to curled paper stock without excessive shift in the position of the vacuum shoe nozzle.

A further concept is that the vacuum shoes may be made adjustable for tilt in all directions by mounting the shoes on a cross bar and mounting the cross bar on the downwardly extending arms in a rotatable manner. The vacuum shoes are tilted laterally of the press by tilt laterally of the cross bar and are tilted longitudinally of the press by rotation of the cross bar. A still further concept is to use relatively short vacuum shoes of a wellknown contractible type having rubber suction pads. The rubber suction pads are highly elfective for picking up paper and especially so because the pads are flexible to accommodate themselves to the surface of the paper even when the paper is not perpendicular to the vacuum shoes. Each vacuum shoe contracts upward in response to vacuum engagement with a sheet of paper and thus the movement of the suction pad on a vacuum shoe in feeding a sheet of paper to the press is a composite of the contraction movement of the shoe plus the movement of the shoe itself as determined by the rocker arms and the motion bar on which the rocker arms are mounted.

Patented Feb. 9, l fid While the invention may be incorporated in the factory fabrication of a printing press, a special feature of the invention is that it may be embodied in a kit for converting an existing printing press of the duplicator type to the new kind of paper feeding operation. For the purpose of the present disclosure, the invention is described as embodied in such a conversion kit.

The features and advantages of the invention may be understood from the following detailed description and the accompanying drawings.

In the drawings, which we to be regarded as merely illustrative:

P16. 1 is a perspective view showing the new feed mechanism mounted on a conventional motion bar of a well known type of printing press of the duplicator type;

FlGS. 1a and 1b are elevational views of springs that may be included in the conversion kit;

FIG. 2 is a perspective view of the mechanism already existing in the printing press for operating the motion bar of the printing press;

FIG. 3 is a diagrammatic side elevational view of the same mechanism and the motion bar operated thereby;

FIG. 4 is an enlarged side elevational View of one of the vacuum shoes that is employed in the preferred practice of the invention;

PEG. 5 is a similar view on a smaller scale showing how the vacuum shoe may be tilted laterally relative to the cross bar in which it is mounted;

FIG. 6 shows the same tilted vacuum shoe as seen along the line 6-6 of FIG. 5;

FIG. 7 is a side elevation of a vacuum shoe showing how it may be tilted longitudinally of the printing press by adjustable rotation of the cross bar on which the vacuum shoe is mounted; and

FIG. 8 is a fragmentary view partly in section and partly in side elevation showing how the cross bar is rotatably mounted at each of its ends on the corresponding rocker arm that extends downward from the motion bar of the printing press.

FIG. 1 shows the presently preferred embodiment of the converter kit of the invention and FIGS. 2 and 3 show the conventional feed mechanism of a duplicator type printing press for which the kit is designed.

Referring to FIGS. 2 and 3 the conventional mechanism of the printing press includes a horizontal transverse motion bar 10 which is at a substantial elevation above the plane of the feed belts of the printing press, which motion bar conventionally carries a pair of spaced downwardly extending vacuum shoes (not shown) of conventional construction, the shoes being relatively long to reach down to the level of a supply stack of paper stock. Such a vacuum shoe comprises a rigid tubular metal casting that is open at its lower end and is connected to a vacuum source for picking up sheets from a supply stack in a well known manner.

The motion bar it} is mounted on the outer ends of a pair of rocker arms 12 that are carried by a transverse rocker shaft 14. The rocker shaft 14 is oscillated by a cam 15 and for this purpose has an actuating arm 16 which rides on a surface 18 of the cam, the actuating arm being held against the cam surface by a suitable coiled tension spring 29. The cam 15 is mounted on a pivot 22 and is oscillated in synchronism with the operating cycle of the printing press by means of an actuating crank 24 and a link 25 that interconnects the cam and the crank. It is apparent that the motion bar ll) is reeiprocated by the two rocker arms 12 along an upright are about the axis of the rocker shaft 14.

The motion bar It is journalled in bearings 26 in the outer ends of the rocker arms 12 for rotation relative to the rocker arms, the relative rotation of the motion bar being controlled by an arm 2% that extends downward and rearward from one end of the motion bar. The lower swinging end of the arm 28 carries a guide follower 30 of circular cross section which reciprocates in a fixed vertical guide slot 32. A suitable spring 34 biases the arm 28 downward in clockwise direction. It is apparent that the arm 28 cooperating with the guide slot 32 causes the motion bar 10 to oscillate with each arcuate reciprocation of the motion bar.

It will be readily understood how a pair of conventional vacuum shoes mounted on the motion bar 10 would function. At the position of the parts shown in solid lines in FIG. 3 with the motion bar 10 at the lowest point of its arcuate path of reciprocation and with the guide follower 30 at the lower end of the fixed guide slot 32, a conventional vacuum shoe on the motion bar would be at its lower rearward limit position to pick up a piece of paper. As the motion bar 10 is swung unwardly by upward movement of the pair of rocker arms 12, the motion bar is rotated slightly in clockwise direction in the two bearings 26 to swing the lower end of the vacuum shoes upward and forward for delivering the sheet of paper to the printing press.

All of the structure shown in FIGS. 2 and 3 that has been described to this point is conventional in a printing press. To convert such a printing press to the mode of operation of the present invention, the usual conventional vacuum heads are removed from the motion bar 10 and applicants kit assembly shown in FIG. 1 is mounted on the motion bar in substitution for the usual vacuum shoes.

The converter parts shown in FIG. 1 include a pair of downwardly extending arms 35 adapted to be mounted on the motion bar It), a transverse bar 36 that is carried by the lower ends of the two arms 35 and a pair of relatively short vacuum shoes 38. Each of the two downwardly extending arms 35 is suitably adapted for mounting on the motion bar 10 and for this purpose each arm has a base portion of split construction with a separate section 40 for clamping engagement with the motion bar 10. The separate section is releasably secured to the rest of the arm by a pair of socket head screws 42 with intervening lock washers 44. This construction permits the two arms 35 to be mounted rigidly but adjustably on the motion bar without removing the motion bar from its bearings 26.

The transverse bar 36 is preferably square in cross section and is suitably journalled at its opposite ends in the two arms 35 respectively. As best shown in FIG. 8, each end of the transverse bar 36 may be of reduced cross section to form a trunnion 45 which extends through a transverse bore 46 in the corresponding arm 35. At least one of the two trunnions 45 may be drilled and tapped to receive an axial socket head screw 48 equipped with a lock washer 50. Preferably both ends of the transverse bar 36 are provided with screws 48. It is a simple matter to tighten the screws 48 sufficiently to hold the transverse bar 36 at any selected rotary position. The screws 43 may be loosened to change the rotary position of the transverse bar 36 but in practice the rotary position of the transverse bar is changed simply by applying a wrench to the rod to overcome the frictional resistance created by the two screws.

The two vacuum shoes 38 that are mounted on the transverse bar 36 are of a well known construction. Each shoe is shaped to straddle the transverse bar 36 and to be tightened into engagement with the transverse bar by a rearwardly extending thumb screw 52. Each of the vacuum shoes 38 has an upwardly directed nipple 54 for connection to a flexible vacuum hose 55. The converter kit preferably further includes a vacuum manifold 56 to be mounted on a fixed part of the printing press and to be connected to a suitable vacuum source in a well known maner. The two flexible vacuum hoses 55 from the two vacuum shoes 38 are separately connected to the vacuum manifold 56.

Each of the vacuum shoes 33 is of relatively short vertical dimension and has a, wntractible nozzle 58 equipped 1. with a flexible elastomer suction pad 66 of flared configuration. The nozzle 53 is urged downward to its extended position shown in FIG. 1 by a suitable light spring that is concealed within the vacuum shoe. As long as the suction pad 60 is in direct communication with the atmosphere, the nozzle 58 remains extended. As soon as the suction pad 60 makes contact with a piece of paper stock and is thereby cut off from the atmosphere, the pressure inside the nozzle drops abruptly and the nozzle is thereby automatically retracted upward by fluid pressure.

In the preferred practice of the invention the converter kit further includes a spring 62 (FIG. la) to be substituted for the spring 26 of FIG. 3 and a spring 54 (FIG. lb) to be substituted for the spring 34. The original springs 20 and 34 are adequate for the usual feed mechanism but may be relatively weak springs and it is usually desirable to substitute the stronger springs to compensate for the fact that the converter kit increases the inertia load on the motion bar.

The manner in which the described converter kit serves its purpose may be readily understood from the foregoing description. It is a simple matter to remove the conventional vacuum shoes from the motion bar 10 and to remove the vacuum hoses that are connected to the vacuum shoes. With the two conventional vacuum shoes removed from the motion bar 19 they are replaced by the W0 arms 35 with the two arms interconnected by the transverse bar 36. The two improved vacuum shoes 38 are then mounted on the transverse bar 35 and the vacuum manifold 56 is mounted on the side of the printing press. The two hoses 55 are then installed to connect the two vacuum shoes 33 with the vacuum manifold 56.

As shown in FIGS. 5 and 6, the two vacuum shoes 38 may be tilted laterally on the transverse bar 36 to conform with any lateral curvature that may characterize some particular printing stock, and the two thumb screws 52 may be loosened temporarily for this purpose. If the printing stock is curled longitudinally instead of laterally the vacuum shoes 38 may be correspondingly tilted longitudinally of the printing press. For this last purpose the transverse bar 36 is rotated on its longitudinal axis as indicated by FIG. 7. Thus, by rotation of the transverse bar about its axis, each of the two vacuum shoes 38 is rotatable for tilt adjustment in a first plane perpendicular to that axis and, in addition, since each vacuum shoe is tiltable on the transverse bar, it is also tiltably adjustable in a second plane perpendicular to the first plane. FIG. 4 shows how the vacuum shoes 38 carry a piece of paper from a supply stack to the feed jaws 65 above the feed belts 66 of the printing press. It is not necessary to adjust the two vacuum heads 38 precisely in accord with the curvature or curl of the printing stock, however, because the suction pads ea are extremely flexible and readily accommodate themselves to paper sheets at various inclinations relative to the nozzles.

It is apparent that whereas the replaced conventional vacuum shoes merely oscillate about the axis of the motion bar as that axis reciprocates along the upright arc, the substituted vacuum shoes 33 are translated bodily over a path that is the resultant of the swinging movement of the arms 35 and the arcuate translation of the motion bar. This changed path is advantageous in combination with the capability of the nozzles 58 to contract. The fact that the nozzles 58 are yieldably contractible permits the vacuum shoes to accommodate themselves to the feed stock through a range of levels. Thus the location of the uppermost sheet of a supply stack is not critical with respect to the pick-up action of the two vacuum shoes 38. The new feed mechanism is inherently reliable for troublefree operation and will operate in a reliable manner even when the two vacuum shoes 38 do not have the optimum tilt for the particular curl of the feeding stock.

My description in specific detail of the presently preferred embodiment of the invention will suggest various changes, substitutions and other departures from my disclosure within the spirit and scope of the appended claims.

I claim:

1. A converter kit for a printing press of the duplicator type wherein the horizontal motion bar of the press conventionally carries relatively long downwardly extending vacuum shoes and is actuated by cam means in opposition to relatively weak spring means for reciprocation through a generally upright arc with simultaneous oscillation about its axis, said kit including:

two relatively long arms adapted for mounting on said motion bar in downwardly extending position in substitution for said relatively long Vacuum shoes to be simultaneously arcuately translated and swung by the motion bar;

a transverse bar mounted on the ends of the two arms;

a pair of relatively short vacuum shoes mounted on said transverse bar for adjustment movement along the length of the bar and extending downward therefrom for connection to a vacuum-engendering means, each of said shoes being rotatable for tilt adjustment in a first plane perpendicular to the axis of the transverse bar and additionally rotatable for tilt adjustment in a second plane perpendicular to the first plane; and

relatively heavy spring means to replace said relatively weak spring means to compensate for the additional load on the motion bar imposed by the two arms and the transverse bar.

2. A converter kit for a printing press of the duplicator type wherein the horizontal motion bar of the press conventionally carries relatively long downwardly extending vacuum shoes and is actuated by cam means in opposition to relatively weak spring means for reciprocation through a generally upright arc with simultaneous oscillation about its axis, said kit including:

two relatively long arms adapted for mounting on said motion bar in downwardly extending position in substitution for said relatively long vacuum shoes to be simultaneously arcuately translated and swung by the motion bar;

a transverse bar journalled in the lower ends of said two arms for rotational adjustment about the axis of the transverse bar;

a pair of relatively short vacuum shoes mounted on said transverse bar for adjustment movement along the length of the bar and extending downward therefrom for connection to a vacuum-engendering means, said relatively short vacuum shoes having elastomer suction pads retractible upward in response to lowering of pressure therein by contact of the suction pads with printing stock; and

relatively heavy spring means to replace said relatively Weak spring means to compensate for the additional load on the motion bar imposed by the two arms and the transverse bar.

3. A converter kit as set forth in claim 2 which includes adjustable screw means to vary the resistance to rotational adjustment of the transverse bar about its axis.

4. A feed mechanism for a printing press of the duplicator type wherein a horizontal motion bar heretofore used to directly carry relatively long vacuum shoes is reciprocated through an upright arc and is rotated on its axis in the course of its reciprocation, said feed mechanism including:

two relatively long arms adapted for mounting on said motion bar in downwardly extending position in substitution for said relatively long vacuum shoes to be simultaneously arcuately translated and swung by the motion bar;

a transverse bar mounted between said two arms; and

a pair of relatively short vacuum shoes mounted on said transverse bar for adjustment movement along the length of the bar and extending downward therefrom for connection to a vacuum-engendering means, each of said shoes being rotatable for tilt adjustment in a first plane perpendicular to the axis of the transverse bar and additionally rotatable for tilt adjustment in a second plane perpendicular to the first plane.

5. A feed mechanism as set forth in claim 4 in which said relatively short vacuum shoes have elastomer suction pads, said suction pads being retractible upward in response to lowering of pressure therein by contact of the pressure pads with printing stock.

6. A feed mechanism as set forth in claim 5 in which said transverse bar is journalled between said two arms for rotational adjustment about its axis to vary the inclination of the relatively short vacuum shoes about said axis; and

in which said relatively short vacuum shoes are rotatable laterally on said transverse bar to various angles relative to said axis.

7. A feed mechanism as set forth in claim 2, in which said pair of relatively short vacuum shoes are adjustable to tilt in a plane that includes the axis of the transverse bar and extends radially of the axis.

8. A converter kit for a printing press of the duplicator type wherein the horizontal motion bar of the press conventionally carries relatively long downwardly extending vacuum shoes and is actuated by cam means in oppo sition to relatively weak spring means for reciprocation through a generally upright arc with simultaneous oscillation about its axis, said kit including:

two relatively long arms adapted for mounting on said motion bar in downwardly extending position in substitution for said relatively long vacuum shoes to be simultaneously arcuately translated and swung by the motion bar;

a transverse bar journaled between said two arms for rotation about the axis of the transverse bar;

means to releasably fix the transverse bar relative to the two arms at selected positions of rotation of the transverse bar;

a pair of short vacuum shoes straddling said transverse bar for adjustment movement along the length of the bar and for tilt in a plane through the axis of the transverse bar; and

means to releasably immobilize the vacuum shoes at selected angles of tilt in said plane.

References Cited in the file of this patent UNITED STATES PATENTS 774,968 McKee Nov. 15, 1904 1,460,314 Deck June 26, 1923 1,518,522 Krejca Dec. 9, 1924 1,717,454 Kelly June 18, 1929 2,850,279 Stoothofi et a1 Sept. 2, 1953 

1. A CONVERTER KIT FOR A PRINTING PRESS OF THE DUPLICATOR TYPE WHEREIN THE HORIZONTAL MOTION BAR OF THE PRESS CONVENTIONALLY CARRIES RELATIVELY LONG DOWNWARDLY EXTENDING VACUUM SHOES AND IS ACTUATED BY CAM MEANS IN OPPOSITION TO RELATIVELY WEAK SPRING MEANS FOR RECIPROCATION THROUGH A GENERALLY UPRIGHT ARC WITH SIMULTANEOUS OSCILLATION ABOUT ITS AXIS, SAID KIT INCLUDING: TWO RELATIVELY LONG ARMS ADAPTED FOR MOUNTING ON SAID MOTION BAR IN DOWNWARDLY EXTENDING POSITION IN SUBSTITUTION FOR SAID RELATIVELY LONG VACUUM SHOES TO BE SIMULTANEOUSLY ARCUATELY TRANSLATED AND SWUNG BY THE MOTION BAR; 